Valve construction and system utilizing the same

ABSTRACT

A three-way changeover valve construction having a housing means provided with an inlet and a pair of outlets. A pair of valve seats are carried by the housing for respectively controlling fluid flow from the inlet through the outlets. A pair of valve members are provided for respectively controlling the valve seats with the valve members being operatively associated together to move substantially in unison relative to the valve seats in response to a condition sensed by a condition responsive device. A changeover device is operatively associated with the valve members to position the same to act respectively on one side of the pair of valve seats or on the other side of the pair of valve seats to change the valve construction from a cooling function thereof to a heating function thereof in response to a temperature change in the flowing medium.

This is a division of copending application Ser. No. 290,558, filedSept. 20, 1972, now U.S. Pat. No. 3,818,981.

This invention relates to an improved valve construction as well as to asystem utilizing such a valve construction or the like.

It is well known that three-way valve constructions can be utilized in aheating-cooling system wherein the valve construction has one outletthereof connected to the heat exchanger coil and another outlet thereofinterconnected to a coil bypass while the single inlet thereof isadapted to be interconnected to a supply of water that is hot during theheating season and chilled during the cooling season. During the heatingseason, a drop in zone temperature causes the valve to increase the flowof hot water to the heat exchanger coil while in the cooling season adrop in zone temperature causes the valve to decrease the flow ofchilled water to the heat exchanger coil.

In the past, valve constructions capable of accomplishing the abovefunctions have been bulky, complicated and expensive.

Accordingly, it is a feature of this invention to provide a valveconstruction that is simple, compact, has relatively few parts which areeasily assembled, and, accordingly, is relatively inexpensive.

It is also a feature of this invention to provide a valve constructionthat has the additional advantages of extreme flexibility wherein theinlets and outlets can be assembled in selected angular relation to eachother so that the valve construction is easily adapted to anyinstallation. This feature also provides for easy alteration of theangular relation of ports in the field.

In particular, one embodiment of this invention provides a valveconstruction comprising a housing means having an inlet and a pair ofoutlets. A pair of valve seat means are carried by the housing means forrespectively controlling fluid flow from the inlet to the outlets. Apair of valve member means are provided for respectively controlling thevalve seat means and the valve member means are operatively associatedtogether to move substantially in unison with each other. Means areoperatively associated with the valve member means to position the sameto act respectively on one side of the pair of valve seat means for acooling operation or on the other side of the pair of valve seat meansfor a heating operation. Such changeover means for so positioning thevalve member means can comprise a temperature responsive device that isresponsive to the temperature of the fluid being supplied to the inletof the valve construction. Regardless of which side the valve membermeans are acting on the pair of valve seat means, a condition responsivedevice is carried by the housing means for causing modulation of thefluid flow through the valve seat means by moving the valve member meansrelative to the valve seat means in response to the condition beingsensed, such as the temperature output effect of the heat exchanger coilbeing supplied heated or chilled water by the valve construction.

Accordingly, it is an object of this invention to provide an improvedvalve construction having one or more of the novel features set forthabove or hereinafter shown or described.

Another object of this invention is to provide an improved controlsystem utilizing such a valve construction or the like.

Other objects, uses and advantages of this invention are apparent from areading of this description, which proceeds with reference to theaccompanying drawings forming a part thereof and wherein:

FIG. 1 is a cross-sectional view of the improved valve construction ofthis invention utilized in a cooling-heating system that isschematically illustrated in FIG. 1.

FIG. 2 is a view similar to FIG. 1 and illustrates the valveconstruction when changed over to the heating cycle thereof whereas FIG.1 illustrates the valve construction in the cooling cycle thereof.

FIG. 3 is a view similar to FIG. 1 and illustrates another embodiment ofthe valve construction of this invention.

FIG. 4 is a fragmentary view of the top part of the valve constructionof FIG. 3 with bellows assembly removed and replaced by an end cap.

While the various features of this invention are hereinafter describedand illustrated as being particularly adaptable for providing a valveconstruction for controlling a heating-cooling system, it is to beunderstood that the various features of this invention can be utilizedsingly or in any combination thereof to provide a valve construction forother systems as desired.

Therefore, this invention is not to be limited to only the embodimentillustrated in the drawings, because the drawings are merely utilized toillustrate one of the wide variety of uses of this invention.

Referring now to FIG. 1, the improved valve construction of thisinvention is generally indicated by the reference numeral 10 and isillustrated as being utilized as a changeover valve for aheating-cooling system generally indicated by the reference numeral 11.The system 11 comprises a heat exchanger coil 12 which is adapted tohave chilled water supplied therethrough from a supply conduit 13through the valve construction 10 in a manner hereinafter described toprovide a cooling operation and during the heating season is adapted tohave hot water supplied therethrough from the supply conduit 13 throughthe valve construction 10 in a manner hereinafter described.

The valve construction 10 comprises a housing means that is generallyindicated by the reference numeral 14 and is formed from a plurality oftubular sections 15, 16 and 17 generally disposed in stacked alignedrelation and being compacted between end plate means 18 and 19 that aresecured together by a plurality of screws or fastening members 20passing through suitable openings in the upper end plate 18 and beingthreaded into suitable threaded openings in the lower end plate or yoke19 as illustrated to secure the tubular sections 15, 16 and 17 together.The sections 15, 16 and 17 are adapted to be rotated in any rotationalposition relative to each other so as to respectively position couplingfittings 21, 22 and 23 carried thereby in the desired angular positionsrelative to each other as well as to the housing means 14 to facilitatethe coupling of the fittings 21-23 in the control system 11 or othercontrol system as desired.

The housing means 14 includes an end member 24 disposed between theupper end plate means 18 and the upper end of the tubular section 15with such end member 24 closing off the upper open end of the tubularsection 15 while having a rubber gasket 25 disposed therebetween toprovide a seal when the upper part of the device 10 is removed as willbe apparent hereinafter.

Similarly, a resilient valve seat member 26 is adapted to be disposedbetween cooperating portions 27 and 28 of the tubular sections 15 and 16which thereby position and hold the resilient valve seat 26 within thehousing means 14, which at the same time resilient valve seat member 26serves as a gasket preventing leakage between tubular sections 15 and16.

Another valve seat member 29 is held between the lower and upper ends ofthe tubular sections 16 and 17 as illustrated, the valve seat member 29having a tubular part 30 extending therefrom and inwardly down theinside peripheral surface of the tubular section 17 to abut againstanother washer-like valve seat member 31 and hold the same against anannular shoulder 32 on the tubular section 17 as illustrated. Valve seatmember 29 is made of plastic or other suitable material such that itforms a gasket where it engages tubular sections 16 and 17 thuspreventing leakage therefrom.

The two valve seat members 29 and 31 respectively have valve seats orvalve ports 33 and 34 passing therethrough to be controlled in a mannerto be hereinafter described, the valve seat members 29 and 31cooperating together to define a lower valve seat means that isgenerally indicated by the reference numeral 35 in the housing means 14while the valve seat member 26 defines upper valve seat means in thehousing 14 and which is generally indicated by the reference numeral 36.

A valve member 37 is disposed in the housing means 14 and has aplurality of fins or guides 38 extending from the upper side 39 thereofand being disposed in sliding engagement with the internal peripheralsurface of the tubular section 15 as illustrated, the valve member 37having a stem 40 extending from the other side 41 thereof and projectingtoward the lower valve seat means 35.

Another valve member 42 is disposed intermediate the valve seats 33 and34 of the valve seat means 35 as illustrated in FIG. 1 and has aplurality of fin-like guides 43 extending from the upper side 44 thereofand passing through the valve seat 33 so as to guide movement of thevalve member 42 in its movement from the valve seat 33 to the valve seat34 between the positions thereof illustrated in FIGS. 1 and 2. The side44 of the valve member 42 has an opening 45 therein which receives theend 46 of the stem 40 as illustrated. A compression spring 47 has oneend 48 bearing against the end plate 19 and the other end 49 bearingagainst the valve member 42 to tend to urge the valve member 42 intocontinuous engagement with the stem 40 of the valve member 37 so thatthe valve members 42 and 37 tend to move in unison relative to thehousing means 14.

Another compression spring 50 has one end 51 bearing against the valveseat member 29 and the other end 52 thereof bearing against the valvemember 37 to tend to urge the valve member 37 upwardly in the drawingsin the same direction that the other spring 47 is tending to urge theother member 42 for a purpose hereinafter described.

A cap or cup-shaped member 53 has its open end 54 disposed over anupwardly directed projection 55 of the end member 24 and is securedthereto in any suitable manner, such as by a wire clip 56 asillustrated. A bellows 57 is disposed within the end cap 53 and has itslower open end 58 interconnected to an annular plate 59 that is sealedin the open end 54 of the cup 53 while its upper closed end 60 isdisposed within a chamber 61 defined within the end cap 53.

An actuating pin 62 is disposed within the interior of the bellows 57and has its upper end 63 bearing against the closed end 60 of thebellows 57 while its lower end 64 passes through the annular washer 59and a suitable opening 65 passing through the end member 24 and into thetubular housing section 15 as illustrated to bear against a flange orplate 66 carried at the upper end of a cylindrical cage 67. If desired,dynamic O-ring seals 68 can be disposed within the opening 65 in the endmember 24 and through which the actuating pin 62 passes in order toprevent any liquid from within the housing 14 from passing into theinterior of the bellows 57. A snap ring 65' is carried by actuating pin65 to prevent pin 62 from being removed or being blown out by pressurewhen the bellows 57 and its assembly is removed.

A flanged cup 69 is disposed within the cage 67 and is normally biaseddownwardly by a compression spring 70 that is disposed within the cage67 and has its upper end 71 bearing against an inwardly turned portion72 of the cage 67 and its lower end 73 bearing against an outwardlyturned flange 74 at the open end of the cup 69 as illustrated to tend tourge the cup 69 against a split washer 75 disposed in the bottom of thecage 67 against an inwardly turned lower end 76 thereof as illustrated.

A thermal element 77 is disposed within the cup 69 and comprises a bodyor housing 78 having a piston rod 80 extending out of the upper end 79thereof. A large cylindrical lower part 81 of the body 78 of the thermalelement 77 is received within suitable notches 82 formed in the guidefins 38 of the valve member 37 as illustrated so as to tend to move inunison with the valve member 37. An intermediate reduced cylindricalpart 83 of the body 78 of the thermal element 77 loosely passes throughthe washer 75 of the cage 67 and positions a larger cylindrical upperpart 84 of the body 78 of the thermal element 77 within the cup 69.

The thermal element 77 and cage 67 provides a length changeable linkbetween the actuating pin 62 and the valve members 37 and 42 forchangeover purposes hereinafter described.

The thermal element 77 contains a wax charge which will expand upon anincrease in temperature to force the piston 80 out of the body 78 andupon cooling will contract and permit an external force on the piston 80to force the piston 80 back into the body 78 as illustrated in FIG. 1.

A resulting shoulder 85 between the body parts 84 and 83 of the thermalelement 77 is engageable with the lower washer 75 of the cage 67 toprovide a stop for the thermal element 77 and accurately control theoverall length of the cage structure between the actuating pin 62 andthe valve member 37 as will be apparent hereinafter.

The details of the structure and operation of the thermal element 77 arewell known and need not be further described in detail. However, it hasbeen found according to the teachings of this invention that such athermal element 77 when utilizing an expanding charge to extend a pistonhas an inherent disadvantage when it is emersed in a liquid under highstatic pressure for extended periods with the charge contracted and noload on the piston thereof. Under these conditions, the liquid leaksalong the piston and collects beneath it to change the effective strokeof the piston upon subsequent expansion of the charge. This leakage isnot a problem when the charge is expanded and exerting a force on thepiston. Accordingly, this invention provides means for isolating thepiston 80 from the surrounding liquid when the charge in the terminalelement 77 is contracted.

In particular, an annular gasket 86 is positioned in the closed end ofthe cup 69 and is engageable by the upper end of the body portion 84 ofthe thermal element 77 when the piston 80 is fully retracted asillustrated in FIG. 1 by the force of the compression spring 50maintaining a positive seal against the closed end of the cup 69 againstthe annular gasket 86.

The fitting 22 of the tubular section 16 of the housing means 14comprises an inlet for the valve construction 10 and is adapted to becoupled to the water supply conduit 13 in any suitable manner. Thefitting 23 of the tubular section 17 of the housing 14 comprises anoutlet of the valve construction 10 and is adapted to be coupled to theheat exchanger coil 12 in any suitable manner to thereby direct fluidthrough the heat exchanger coil 12. The fitting 21 of the tubularsection 17 of the housing 14 comprises a by-pass outlet adapted to beinterconnected to a coil by-pass conduit 87 in any suitable manner sothat any fluid being directed out of the outlet 21 will by-pass the heatexhanger coil 12.

The interior chamber 61 of the upper cup or cap 53 of the housing means14 is adapted to be fluidly interconnected by a conduit means 88 to atemperature sensing bulb 89 positioned to sense the temperature of thespace being controlled by the heat exchanger 12 so that the fluid in thechamber 61 acting on the bellows 57 expands upon a sensed increase inthe output temperature effect of the coil 12 and contracts upon a senseddecrease in output temperature effect of the coil 12 for a purposehereinafter described.

From the preceding description of the valve construction 10 and itsinterconnection in the system 11, it can be seen that the valveconstruction 10 can be formed of a plurality of relatively simple partsdisposed in stacked and aligned relation in the housing means 14 withthe inlet 22 and outlets 21 and 23 thereof adapted to be rotationallypositioned relative to each other to provide different angles relativeto the housing means 14 before the same are secured in place by thefastening members 20.

The operation of the valve construction 10 of this invention as utilizedin the control system 11 will now be described.

When the system is set in the cooling mode as illustrated in FIG. 1,chilled water is supplied to the inlet 22 by the conduit means 13. Thechilled water cools the body 78 of the thermal element 77 causing thewax charge therein to contract and position the piston 80 in the fullyretracted position illustrated in FIG. 1. The relative position of thevarious parts of the cage 67 and thermal element 77 is such that thesame is in its shortest linkage configuration between the actuating pin62 and the valve member 37. Also, the parts illustrated in FIG. 1 are inthe position when the system 11 is fully satisfied, i.e., the outputtemperature effect of the coil 12 is at or below desired coolingtemperature effect thereof so that the fluid in the bulb 89, and thus,in the chamber 61 of the end cap 53 is in its most contracted conditionwhereby the bellows 57 is in its most expanded condition and permits thespring means 50 and 47 to urge the valve members 42 and 37 upwardlyuntil the valve member 42 fully seats against the valve seat 33 toprevent further upward movement thereof and the spring 50 has caused thevalve member 37 to move upwardly to fully move the cage 67 to itsuppermost position for the satisfied condition illustrated and maintainthe seal around the piston 80 of the thermal element 77 for the purposepreviously described.

Thus, with the valve member 42 fully seated on the valve seat 33, nochilled water from the inlet 22 is directed through the coil 12 as theentire amount of chilled water being supplied to the inlet 22 goesthrough the valve seat 26 to the by-pass outlet 21, the valve member 37being so positioned in FIG. 1 that the same provides full flow throughthe by-pass valve seat 26 to the by-pass outlet 21.

However, an increase in temperature being sensed by the bulb 89 willcause expansion of the liquid charge therein and a flow of liquid intothe chamber 61 to compress the bellows 57. This causes downward movementof the entire assembly of the actuator pin 62, cage 67 and thermalelement 77 which moves the valve disc 37 toward the valve seat 26 andthe valve member or disc 42 away from the valve seat 33 a certainamount. This results in an increase in flow of chilled water through theoutlet 23 to the coil 12 and a decrease in the flow of chilled waterfrom the inlet 22 to the by-pass outlet 21 to tend to lower the outputtemperature effect of the coil 12. However, a further temperatureincrease at the bulb 89 will move the valve disc 42 farther from thevalve seat 33 and position the valve disc 37 closer to the by-pass valveseat 26 to increase the flow of chilled water to the coil 12 anddecrease the flow of chilled water to the by-pass outlet 21. As theincrease in output temperature effect of the coil 12 causes the valvemember 37 to approach the valve seat 26, a fluid-tight seal is noteffected between the valve disc 37 and the valve seat 26 but a slightleakage to the by-pass 21 has little effect on the operation of thesystem 11. However, an advantage of this slight leakage through thevalve seat 26 at this time is that the thermal element 77 will alwayssense supply water temperature.

It can be seen that when the increase in temperature being sensed by thebulb 89 positions the upper valve member 37 to substantially close thevalve seat 26, the valve member 42 has been moved away from the valveseat 33 a distance sufficient to provide complete fluid flowtherethrough as the valve member 42 is only intermediate the valve seats33 and 34 so that the same does not cause the valve seat 34 to closeduring such full cooling operation of the valve construction 10. It canbe seen that a further increase in temperature sensed at bulb 89 wouldcause valve member 37 to go through valve seat 26 opening up the by-passwhile valve member 42 would proceed to restrict flow to the heatexchanger coil 12 by approaching valve seat 34 were it not for plate 66of cage 67 engaging shoulder 66' at a proper position to prevent thisfrom happening.

Conversely, a decrease in temperature at the bulb 89 will cause upwardmovement of the valve members 37 and 42 to decrease the flow of chilledwater to the coil 12 and increase the flow of chilled water to theby-pass 21.

Thus, it can be seen that during the cooling operation of the system 11with the valve construction 10 in the condition illustrated in FIG. 1,the bellows 57 and actuating pin 62 provides a condition responsivemeans responsive to the condition being sensed by the bulb 89 to causemovement of the valve members 37 and 42 relative to the upper sides ofthe valve seat means 36 and 35 to control the flow of fluid from theinlet 22 to the outlets 21 and 23.

When the system 11 is changed over to the heating mode thereof, hotwater is supplied to the inlet 22 by the conduit 13 and the hot water inthe housing 14 heats the body 78 of the thermal element 77 to expand itswax charge and force the piston 80 to its extended position asillustrated in FIG. 2. Extension of the piston 80 causes downwardmovement of the body 78 of the thermal element 77 until the shoulder 85thereof seats on the split washer 75 because overrun spring 70 has aheavier load than the combined load of springs 47 and 50. Thereafter,further expansion of the piston 80 causes the compression of spring 70to the position illustrated in FIG. 2. Thus, the linkage provided by thecage 67 and the thermal element 77 is then at its maximum length betweenthe actuating pin 62 and the valve member 37 with the relative positionof the parts being as illustrated in FIG. 2.

During the changeover of the valve construction 10 from the cooling modeillustrated in FIG. 1 to the heating mode illustrated in FIG. 2, thevalve element 37 is moved downwardly against the bias of the springs 50and 47 and passes through the resilient valve seat 26 and if the system11 is fully satisfied as illustrated in FIG. 2, the valve member 42bottoms out against the valve seat 34 to close the same while the valvemember 37 is passed completely through the valve seat 26 to provide aposition for full fluid flow therethrough.

With the system 11 fully satisfied in the heating mode illustrated inFIG. 2, the temperature sensing bulb 89 is sensing an output temperatureeffect of the coil 12 at or above the desired temperature so that thefluid in the chamber 61 of the end cap 53 is at its maximum volume andhas forced the bellows 57 downwardly and, thus, the actuating pin 62downwardly to the position illustrated in FIG. 2 to maintain the valvemember 42 against the valve seat 34 so that the entire flow of hot waterfrom the inlet 22 passes through the by-pass valve seat 26 to theby-pass outlet 21.

A decrease in output temperature at the bulb 89 below the desired outputtemperature effect will cause constriction of the liquid charge in thebulb 89 and, thus, expansion of the bellows 57 with a correspondingupward movement of the actuating pin 62, cage 67, thermal element 77 andthe valve members 37 and 42 under the force of the compression springs50 and 47. This moves the valve disc 42 away from the valve seat 34 topermit some hot water to flow to the outlet 23 and, thus, to the coil 12to tend to increase its output temperature effect while the valve disc37 moves toward the by-pass valve seat 26 to reduce the flow of hotwater to the by-pass outlet 21. Similar to the cooling situation, afurther decrease in temperature sensed at bulb 89, FIG. 1, would throwthe valve into reverse operation except that plate 66 engages gasket 25at a position to prevent this from happening. A further decrease inoutput temperature effect moves the valve disc 42 upwardly farther fromthe seat 34 to increase the flow of hot water to the coil 12 andpositions the valve disc 37 immediately adjacent the valve seat 26 toreduce the flow of hot water to the by-pass outlet 21 to a minimum.Conversely, an increase in temperature at the bulb 89 will cause thebellows assembly 57 to move the valve element 42 downward toward thevalve seat 34 to reduce the flow of hot water to the coil 12 andincrease the flow to the by-pass 21 by correspondingly moving the valvemember 37 farther away from the valve seat 26.

When the system is again changed back to the cooling mode illustrated inFIG. 1, the chilled water supplied to the inlet 22 cools the body 78 ofthe thermal element 77 and causes contraction of its wax charge. Thispermits the springs 70 and 50 to compress the cage 67 and thermalelement 77 to its shortest dimension forcing the piston 80 into the body78 and moving the valve disc 37 through the valve seat 26. With theparts in these positions, the end of the body 78 of the thermal element77 is seated on the sealing gasket 86 to seal the piston 80 from thewater in the system.

Thus, it can be seen that the valve construction 10 of this invention isreadily adapted to control the heat exchanger system 11 and cause achangeover from the cooling cycle thereof to the heating cycle thereofwith the valve members 37 and 42 acting on one side of the pair of valveseat means 36 and 35 for a cooling operation of the system 11 and actingon the other side of the valve seat means 36 and 35 for a heating cycleof operation of the system 11.

Also, it can be seen that the valve construction 10 of this invention iseasily assembled as the assembly thereof merely amounts to a simplestacking of the parts together. In particular, the valve construction 10is assembled upside down starting with the bellows assembly 57 followedby the yoke or upper end plate 18, cap 53, actuating pin 62, washer 25,extensible linkage subassembly 67, 77, valve body section 15, valveelement 37, valve seat 26, valve section 16, spring 50, valve seatmember 29, valve member 42, valve seat member 31, valve section 17,spring 47, end cap 19 and securing members 20.

Each of the three valve body sections 15, 16 and 17 can be positioned inany one of four angular positions between the securing members 20 toproduce the desired body configuration and then the securing members 20can be installed to secure all of the parts in place as illustrated.

Thus, the valve body sections 15, 16 and 17 can be selectivelypositioned before the securing members 20 are installed. However, thevalve body can be readily modified in the field by removing at least onefastening member 20 and loosening the others so that the valve sections15, 16 and 17 can be rotated to the desired position. Thereafter thesecuring members 20 are tightened.

It can be seen that in order to prevent the power element 77 fromunloading when the bellows arrangement 57 cools sufficiently with coldwater being supplied at inlet 22 for the valve member 42 to go againstthe upper seat 33 as illustrated in FIG. 1, the spring 50 is adapted toact upwardly to maintain a load on the power element 77 to maintain theupper end thereof in sealing relation with the sealing gasket 86 so asto exclude water from the interior of the power element 77 when highstatic pressures are present.

Another valve construction of this invention is generally indicated bythe reference numeral 10A in FIGS. 3 and 4 and parts thereof similar tothe valve construction 10 are indicated by like reference numeralsfollowed by the reference letter A.

As illustrated in FIG. 3, the end wall member 24A of the housing means14A of the valve construction 10A is modified from the form illustratedin FIGS. 1 and 2 so as to be provided with three depending guide legs100 extending within the tubular housing member 15A whereby the legs 100guide reciprocal movement of the cage 67A of the change over assembly.Thus, the cage 67A does not carry the upper plate 66 as in theembodiment of FIGS. 1 and 2 because other means are provided forcontrolling the movement of the cage 67A to prevent the valveconstruction 10 from going into a reverse operation on a heating orcooling cycle as was provided by the end plate 66 and shoulder means 66'or gasket 25 as previously described.

The actuating pin 62A of the valve construction 10A is formed of twoparts 101 and 102 for a purpose hereinafter described with the parts 101and 102 being disposed in aligned abutting relation. An O-ring 103 isdisposed about the lower end 104 of the lowermost part 102 to provide aback-seat against which the closed end 105 of the cage 67A will engageunder the force of the compression spring 70A to prevent fluid leakagewhen the stem 62A is removed for packing replacement purposes. Forexample, the end piece 24A has a chamber 106 provided therein and inwhich is disposed the sealing packing means 107.

The end plate member 24A has a part 108 thereof formed as a scraper toclean the stem part 102 as it moves back and forth in the end plate 24Awhereby the scraper 108 continuously cleans the stem part 102 andthereby helps to prevent wear on the packing 107.

The packing 107 is confined within the chamber 106 of the end plate 24Aby a retaining nut 109 that is threaded onto external threads 110 of anoutwardly projecting portion 111 of the end plate member 24A asillustrated.

An adjustable heating and cooling stop assembly 112 is threaded withinthe retaining nut 109 and confines movement of the stem part 102 withinthe limits of a lower internal shoulder 113 thereof and an upperinternal shoulder 114 thereof because the stem part 102 carries a snapring 115 disposed within the stop assembly 112. The distance between theinternal faces or shoulder 113 and 114 of the stop assembly 112 isexactly calculated so that when the stop assembly 112 is properlyadjusted to account for all tolerance variation in a particular valveassembly, face 113 will prevent the valve construction 10A from goinginto reverse operation on the cooling cycle thereof and the face 114will prevent the valve construction 10A from going into reverseoperation on the heating cycle thereof.

In particular, the valve construction 10A illustrated in FIG. 3 isdisposed in its cooling mode wherein chilled water is supplied to theinlet 22A and when the system is fully satisfied, as illustrated in FIG.1, the output temperature of the heat exchanger is at or below thedesired cooling temperature effect thereof so that the fluid in thechambers 61A of the end cap 53A is in its most contracted conditionwhereby the bellows 57A is in its most expanded condition and permitsthe spring means 50A and 47A to urge the valve members 42A and 37Aupwardly until the valve member 42A fully seats against the valve seat33A to prevent further upward movement thereof and the spring 50A hascaused the valve member 37A to move upwardly to fully move the cage 67Ato its uppermost position for a satisfied condition as illustrated andmaintain the seal around the piston 80A of the terminal element 77A forthe purpose previously described.

Thus, with the valve member 42A fully seated on the valve seat 33A, nochilled water from the inlet 22A is directed to the heat exchanger asthe entire amount of chilled water being supplied to inlet 22A goesthrough the valve seat 26A to the bypass outlet 21A, the valve member37A being so positioned in FIG. 3 that the same provides full flowthrough the bypass valve 26A to the bypass outlet 21A.

However, an increase in temperature being sensed by the temperaturesensing bulb will cause expansion of the liquid charge therein and aflow of liquid into the chamber 61A to contract the bellows 57A. Thiscauses downward movement of the entire assembly of the actuator 62A,cage 67A and thermal element 77A which moves the valve disc 37A towardthe valve seat 26A and the valve member 42A away from the valve seat 33Aa certain amount. As the increase in output temperature effect of theheat exchanger causes the valve member 37A to approach the valve seat26A, further increase in temperature sensed by the bulb would cause thevalve member 37A to go through the valve seat 26A and open up theby-pass while the valve member 42A would approach the seat 34A torestrict the flow to the heat exchanger were it not for the snap ring115 on the stem part 102 engaging against the face of the stop assembly112 to prevent this from happening.

Conversely, when the valve assembly 10A is in the heating mode thereofwherein the valve member 37A is on the lower side of the valve seat 26Ain the same manner as the valve assembly 10 of FIG. 2, a decrease insensed temperature would throw the valve into reverse operation by anattempt to move the valve member 37A through the valve seat 26A exceptfor the fact that the snap ring 115 will engage against the upper face114 of the stop assembly 112 to prevent the valve member 37A frompassing through the valve seat 26A in the same manner as the plate 66engages against the gasket 25 of the valve assembly 10 previouslydescribed to prevent such a reverse operation.

Thus, it can be seen that the stop assembly 112 within the retaining nut109 provides an adjustable stop means for the actuator pin 62A of thevalve assembly 10A to prevent the same from going into reverse operationon both the cooling and heating cycles thereof.

Of course, the above term "reverse operation" refers to a reversal ofnormal flow response, not reverse in the sense of a "direct" or"reverse" acting valve as is commonly used.

The adjustable stop assembly 112 has a tubular guide 116 extendingtherefrom and is utilized to guide the lower end 117 of the upper stempart 101 into alignment with the upper part 118 of the lower stem part102. By having a two part actuating stem 62A, the valve assembly 10A canbe shipped without the thermal system which includes the bellowsassembly 57A in the manner illustrated in FIG. 4 wherein it can be seenthat a cap 119 is threaded on external threads 120 of the retaining nut109, the cap 119 thus protecting the end of the valve assembly 10A andserving as a hand adjustment for use during the construction of buildinginto which the valve construction 10A will be put and before the thermalsystems have been installed. However, when the thermal system is to beinstalled, the cap 119 is removed and thrown away and the bellowsarrangement 57A is provided thereon in the manner illustrated in FIG. 3for the purpose previously described.

As illustrated in FIG. 3, the valve seat member 29A is provided withdownwardly directed guide fins 121 which guide the movement of the valvemember 42A between the valve seats 33A and 34A in the same manner thatthe guide means 43 on the valve member 42 of the valve assembly 10.

A guide washer 122 has been added to the valve stem 40A of the valveconstruction 10A and has a plurality of openings 124 passingtherethrough, the guide washer 122 having its outer periphery 124disposed in sliding relation with the internal peripheral surface 125 ofthe tubular housing section 16A while its inner periphery 126 isdisposed about the stem 40A and is held upwardly against the same by thecompression spring 50A. In this manner, the guide rings 38 of the valvestem 40 of the valve construction 10 of FIG. 1 can be eliminated.

If desired, suitable hex sections 127 can be added to the inlet 22A andoutlet 21A and 23A fittings to facilitate tightening of mating nutsthereon.

Therefore, it can be seen that the valve construction 10A functions insubstantially the same manner as the valve construction 10 previouslydescribed for the change over purpose and prevents adverse reversal ofoperation on heating and cooling cycles thereof through the use of theadjustable stop member 112.

While the form of the invention now preferred has been disclosed anddescribed as required by the patent statute, other forms may be utilizedand all come within the scope of the appended claims.

What is claimed is:
 1. A valve cnstruction comprising a housing meanshaving an inlet and a pair of outlets, a pair of valve seat meanscarried by said housing means for respectively controlling fluid flowfrom said inlet to said outlets, a pair of valve member means forrespectively controlling said valve seat means, said valve member meansbeing operatively associated together to move substantially in unison,and means operatively associated with said valve member means toposition the same to act respectively on one side of said pair of valveseat means or on the other side of said pair of valve seat means, saidpair of valve member means when increasing the fluid flow to either ofsaid outlets will decrease the fluid flow to the other of said outletsregardless of which side said pair of valve seat means said pair ofvalve member means are acting, one of said valve seat means comprising asingle valve seat, said valve member means controlling said single valveseat being movable through said single valve seat as said meanspositions said valve member means respectively between said one side ofsaid pair of valve seat means and said other side of said pair of valveseat means.
 2. A valve construction comprising a housing means having aninlet and a pair of outlets, a pair of valve seat means carried by saidhousing means for respectively controlling fluid flow from said inlet tosaid outlets, a pair of valve member means for respectively controllingsaid valve seat means, said valve member means being operativelyassociated together to move substantially in unison, and meansoperatively associated with said valve member means to position the sameto act respectively on one side of said pair of valve seat means or onthe other side of said pair of valve seat means, one of said valve seatmeans comprising a single valve seat, said valve member controlling saidsingle valve seat being movable through said single valve seat as saidmeans positions said valve member means respectively between said oneside of said pair of valve seat means and said other side of said pairof valve seat means, said single valve seat being formed of flexiblematerial to assist the movement of its respective valve member meanstherethrough.